HP 8920B - Page 333

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Chapter 5, Advanced Operations
Instrument Initialization
Interface Clear (IFC) HP-IB Bus Command
The Interface Clear (IFC) Reset is accomplished by having the Active Controller
send the ABORT message to the HP-IB bus (ABORT message = IFC bus control
line TRUE for 100 ms).
The IFC bus command unconditionally terminates all HP-IB bus activity and the
Test Set is unaddressed.
The IFC bus command has no effect on the I/O CONFIGURE, CONFIGURE,
PRINT CONFIGURE, or TESTS (Main Menu, Execution Conditions, External
Devices, Printer Setup) screens.
Other operational characteristics are also affected by the IFC bus command as
follows:
• The Power-up self-test diagnostics are not performed.
• The HP-IB interface is not reset (any pending Service Request is not cleared).
• The Contents of the SAVE/RECALL registers are not affected.
• Measurement triggering is not affected.
• Calibration data is not affected .
• All Enable registers are unaffected: Service Request, Standard Event, Hardware #1,
Hardware #2, Operation, Calibration,Call Processing and Questionable Data/Signal.
• All Negative Transition Filter registers are unaffected: Hardware #1, Hardware #2, Op-
eration, Calibration,Call Processing and Questionable Data/Signa.l
• All Positive Transition Filter registers are unaffected: Hardware #1, Hardware #2, Op-
eration, Calibration,Call Processing and Questionable Data/Signal.
• The contents of the RAM memory are unaffected.
• The contents of the Error Queue are unaffected.
• The contents of the Output Queue are unaffected.
• The state of the Test Set display screen is not affected